1. Field of the Invention
The present invention relates to an apparatus for continuously producing a strip of dough of constant dimensions at a constant flow rate while the dough is conveyed, and more particularly, to such apparatus whereby a pressure or stirring force imparted to the dough is minimized, and the width and thickness of the dough strip is made uniform.
2. Description of Prior Art
Continuous feeding of a dough having elasticity and viscosity, such as bread dough has hitherto been carried out through extrusion by a screw apparatus, or through suction and extrusion by an extruder with a piston and a cylinder.
These apparatus, however, basically rely upon mechanical forces to form continuous dough strips. An excessive pressure is frequently imparted to the dough fed, or the dough is frequently severed by the screw during stirring.
Such mechanical forces harm the dough structure, especially bread dough. The gel structure of the dough tends to be destroyed due to the pressure or stirring, and an extra step is required to recover the gel structure. Such a step required an extra device, and thus the size of the dough processing apparatus becomes bulky.
The inventor of the present invention invented the apparatus disclosed in (U.S. patent application Ser. No. 718,126 filed on Apr. 1, 1985), in which a variable speed conveyor having a weighing device and a constant speed conveyor arranged downstream of and adjacent to the variable speed conveyor is provided, and two pressing means are disposed above and adjacent the rear end of the variable speed conveyor and the front end of the constant speed conveyor, respectively. The dough is compressed or stretched between two positions where the pressing means are disposed to be made into dough having a constant unit weight.
Furthermore, the inventor invented an apparatus for producing a strip of dough having constant dimensions and a constant flow rate, disclosed in (U.S. patent application Ser. No. 720,760 filed on Apr. 8, 1985 now U.S. Pat. No. 4,583,930), in which a roller mechanism replaced the pressing means disposed above and adjacent the front end of the constant speed conveyor in the apparatus of the first-mentioned patent application.
In the latter patent application, dough defining means was further provided between the straight portion of the roller mechanism and the conveyance path of the constant speed conveyor, and the dough is similarly compressed or stretched between two positions, namely between the portion where the pressing means above the rear end of the variable speed conveyor are located and the position where the dough comes into contact with the roller mechanism.
In either apparatus of these two inventions, although the dough fed between the two positions is effectively compressed by the increased speed of the variable conveyor when the weight of dough per unit length on the variable speed conveyor is smaller than a predetermined value, the dough can not be uniformly stretched when the weight of dough per unit length is larger than the predetermined value.
The dough between the pressing means and the variable speed conveyor is controlled in a region where the pressing means abuts the dough, and, only the dough portion in or near the region can be directly controlled by the pressing means so as to move together with the movement of the pressing means, but, the dough portion leaving the region is not effectively controlled by the pressing means.
Therefore, if there is a relatively thinner portion in the dough, only that portion of dough is stretched, whereby the thinner portion of dough would become thinner. This phenomenon demonstrates that stress is liable to converge on the thinner portion when the dough is stretched.